Speed responsive device of the flyball type



J. T. HUNT 2,544,791

SPEED RESPONSIVE DEVICE OF THE FLYBALL TYPE March 13, 1951 Filed Dec. 27, 1946 v Zhwentor James T. Hun: 9m, 4/ 0%,,

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Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE SPEED RESPONSIVE DEYICEOF THE FLYBALL TYPE James T. Hunt, Arlington, Va.

Application December 27, 1946, Serial No. 718,784

3 Claims. 1

This invention relates to speed-responsive devices, and particularly to a simplified construction of fly-ball governor, suited to a variety of purposes, but intended primarily for use as part of the starting switch mechanism of small electric motors.

The novelty of the device does not concern the main operative function, for that is conventional, but resides in certain details of construction which reduce the number of parts, and permit, great economies in manufacture. These economies arise from the use of simple stampings, and from the fact that assembling operations are so quick and easy that labor costs are low.

A successful embodiment of the invention is illustrated in the accompanying drawing, in which:

Fig. 1 is a side elevation of the device assembled on a motor shaft and in coactive relation with an electric switch.

Fig. 2 is an axial section of the parts shown in Fig. 1, the shaft being shown in elevation and the switch omitted.

Fig. 3 is a perspective view of the yoke.

Fig. 4 is a perspective view of one of the two fly-ball units.

Fig. 5 is an elevation of the switch-actuating collar.

Fig. 6 is a perspective view illustrating anassembling operation.

In the drawing the shaft of an electric motor is indicated at H. The starting switch of the motor comprises spring contact arms [2 and I3 fixed on an insulating support l4. Stating direction with reference to Fig. 1, arm I2 tends to flex to the left and open the circuit which the switch controls. The parts so far described are conventional.

The yoke, generally designated by the numeral 15, is produced from steel strip in two stamping operations, a blanking operation followed by a formin operation. The yoke comprises a crossmember [5 and two arms [I which are shown as parallel. At mid-length of cross-member I5 is a circular aperture IS with flanged margin l9 so dimensioned that the yoke may be pressed onto shaft II and retain itself thereon rigidly in such position that the axis of the shaft is normal to the plane surfaces of the cross-member. In each of the arms I? is a T-shaped slot, which desirably is formed with a rather wide stem-slot 20 and a slender cross-slot 2!, the latter being at that end of the slot which is toward crossmember I6.

Freely slidable on shaft ll toward and from 2 "the cross-member I6, and dimensioned to enter between arms "is a switch-actuating collar generally designated 22 made up of a hub 23,fa small end-flange 24 and a larger end-flange 25. The flange 24 is toward the cross-member l6, and a coil compression speeder spring 26 encircling shaft ll between these parts serves to urge the collar 22 away from the cross-member Hi. The collar 22 is preferably molded in one piece of nonconducting plastic. At the limit of the collars outward (right-hand) motion flange 25 engages a boss on the end of contact I2 and forces it to the right, closing 'the switch.

The fly-ball members 21 are identical stampings produced by a blanking operation and a forming operation. Between the fly-weight portion 28 (which is curved at its tip as best shown in Figs. 1 and 4) and the narrower finger portion 29 is a neck 3| defined by lateral notches. The finger portion 29 is at about to the weight portion 28 and carries at its end a cylindrical thrust portion 32 which is designed to 00- act with the inner face of flange 24.

The angle between portions 28 and 29 is produced by a bend local to neck 3 l. Adjacent this neck and on arm portion 29 (see Fig. 4) are two shoulders 33 which form part of a sort of knifeedge bearing between the fly-ball members 2'! and the inner surface of a corresponding arm I! at the sides of stem-slot 20.

In assembling, the finger portion 29 is inserted through the cross-slot 2|, until neck 3! will enter stem-slot 20. The order of operation is as follows: Yoke I5 is pressed onto shaft H. Speeder spring 25 and collar 22 are slid to place. Then collar 22 is pressed toward cross-member l6, compressing spring 26, until the space between flanges 24 and 25 alines with cross-slots 2|. Then the fingers 29 of two fly-ball members 21 are inserted inward through slots 2| of the two opposite arms IT, as far as they will go (see Fig. 6). Collar 22, when released, shifts the fiy-ball members until their necks 3| are at the ends of slots 29. The parts are then in the position illustrated in Figs. 1 and 2.

When the shaft rotates, the weight portions 28 develop a centrifugal tendency which causes the members 21 to pivot on the shoulders 33 so that fingers 29 react on flange 24 and shift collar 22 to the left, compressing the speeder spring. This allows the switch to open.

It should be observed that speeder spring 25 holds the parts assembled when the shaft II is not rotating. ,When the shaft rotates, the spring and centrifugal effects both maintain the assembled relation. The use of one way thrust bearings to mount the fly-weights in the yoke and the use of the speeder spring reaction to maintain assembled engagement are the features which make simplified construction and quick assembly possible.

There are only five parts, the yoke, two flyweights, the collar and the speeder spring. Of these parts, three are stampings and a fourth is molded in one piece from plastic. Modifications of form are possible without sacrificing the valuable features above disclosed and the invention is not limited strictly to the preferred form above described in detail.

What is claimed is:

1. A centrifugal device comprising a shaft, a

rigid yoke fixedly mounted on said shaft and having diametrically opposed arms symmetrically positioned relatively to the axis of the shaft; a collar shiftable axially on the shaft; a speeder spring reacting between the collar and the yoke; and fiy-weight members hingedly mounted on the arms of the yoke and each having a finger engaging the collar to shift the same against the urge of the speeder spring, said hinged mounting comprising bearing elements on the fly-weight members and on said arms formed to interact in one-way thrust, and maintained in engagement by the reaction of the speeder spring in all functional positions of the fly-weight members.

2. The combination defined in claim 1 in which the arms of the yoke are slotted and the flyweight members are L-shaped and notched in opposite edges at the angle of the L, whereby said fingers can be inserted through respective slots in the yoke to engage the collar and can then be shifted so that the notches enter into retaining engagement with the sides of the slot.

3. The combination defined in claim 1 in which the arms of the yoke are formed with T-shaped slots and the fly-weight members are L-shaped and are notched in their opposite edges at the angle of the L, whereby said fingers may be inserted through the head of the T-slot to engage the collar and then be moved so that the edges of the narrow portion of the T-slot engage in the notches.

JAMES T. HUNT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 852,882 Kerr May 7, 1907 1,432,444 Dake Oct. 17, 1922 1,926,339 Kindl Sept. 12, 1933 2,083,343 Naul June 8, 1937 2,095,755 Tebby Oct. 12, 1937 2,307,539 Pefier Jan. 5, 1943 2,416,973 Wright Mar. 4, 1947 2,460,246 Vacha Jan. 25, 1949 

